There has long been a need for secure documents, that is, documents that cannot be readily copied or counterfeited, or readily altered. As modern technology has progressed, the technology employed by counterfeiters or those who would alter documents for illicit purposes has likewise improved. And, of course, modern society employs a variety of documents for a variety of purposes which can be misused if they can be readily altered, copied or counterfeited.
Of immediate concern as far as the present invention is concerned, is providing a document that is secure against alteration. For example, various forms of documents providing for personal identification such as drivers licenses have been altered, frequently, for the purpose of falsely indicating the birth date of the license holder. Various documents of value, including specifically checks, have been altered to change the stated value of the check.
Other cases where documents may be altered include those where one wishes to alter the date of a document or even alter the signature placed on a document. In each of these cases, it is typically the so-called variable information that is altered.
As is well known, many documents include so-called fixed information which is information that will not change from one document of the same character to the next. For example, the basic format of a common check is fixed information except for that designating the check number. When the check is completed, variable information, including information in the form of the identity of the payee, the signature of the pay or and the amount of the payment as well as the date of the payment is added. This information is termed variable information because it will typically vary from one document to the next, even in the case of the pay or signature as many accounts have more than one signatory who can complete a check.
Quite clearly, it is highly desirable to prevent alteration of such documents so as to prevent misuse of the document. The present invention is directed to accomplishing that goal.